Variable pitch propeller mechanism



R-essued May 30, 1939 PATENT OFFICE l 'VARIABLE PITCH PROPELLER MECHANISM J ohnRapp Zipay, Pittsburgh, Pa.

Original No. 1,998,152, dated April 16, 1935, Se-

rial No. 624,743, July 26, 1932. Application for reissue October 12, 1936, Serial No. 105,350

Claims.

This invention relates to variable pitch propellers and its consists in the constructions, arrangements and combinations herein described and claimed. f

In variable pitch propellers for aeroplane and like uses the stems ofthe propeller blades are 15 ugally acting weights wh'ch revolve with the propeller or levers ext ing radially of the stemsv of the propeller blades and thus the weights increase the air-resistance to the rotation of the propeller, and whereverv located the 2o weights tend to destrqy'.the balanceof the propeller mechanism.

'One of the objects which I have in view is to provide for the automatic control of the variation in propeller blade pitch in accordance with the speed of rotation without'the use of weights or other like meanswhich tend to impair or destroy the balance or which increase the airresistance.

For the purpose I employ the pressure of the forced feed of o'il to the motor of the aeroplanev or other air craft.- In motors used for this purpose the oil is supplied under pressure to the bearings and their moving parts by an oil pump which is driven from the motor, the pump pressure increasing with the speed of the motor and consequently with the speed of rotation ofthe propeller.

In my invention as the oil pump pressure increases with the speed of rotation of the pro- .40 peller the pitch of the propeller blades ls automatically increased and, likewise, as the speed 0f -the motor and consequently the speed of rotation of the propeller and also the pressure of the oil decreases the pitch of the propeller blades is likewise decreased.

I yprovide means whereby both the minimum and the maximum pitch of the propeller blades may be `ldjusted so that the greatestefflciency may be obtained.

Again I provide means whereby the operator in the cockpit -or control car of the aircraft may at will throw the automatic'pitch varying means into and out of operation while in flight. P 55 Other novel features of construction and of arrangement of parts will appear from the following description.

In the accompanying drawing wherein I have illustrated 'a practical embodiment of theI principles of my invention,

Figure 1 is a broken plan view partially in horizontal section along the line'I--I of Figure 2, showing thefront end of the propeller shaft of an aeroplane, the partible propeller hub and the propeller blades having their stems journalled `in lo the bores of the hub.

Figure 2 is a vertical cross section along the line 2-2 in Figure 1.

Figure 3 is a vertical section along the line 3-3,in Figure 1. n 15 Figure 4 is a detail partially in section of one of the head members secured to one of the propeller blade stems.

Figure 5 is a detail in section showing thel manually operated control valve.l 20

Figure 6 is a diagrammatic view showing the motor, the oil pump, and the propeller of an aeroplane.

Referring to the drawing, I represents the propeller shaft which is driven by the motor 2, and the motor also drives the oil pump 3 which supplies oil under pressure to the moving parts.

The partible propeller hub shown at 4a-4b is fixed on and disposed transversely to the shaft I, the bushing parts being held together as by 30 the clamping bands 5.

6 represents the'propeller blades whose stems 1 are journalled in the bore of the propeller hub.

8 represents heads which are provided with integrally and axially disposedtubular necks 9 which have central akal'fopenings I0 contracting in diameter from th'eoit'er endsA of the necks and extendiyhrpug'the heads 8'. The necks are spurgo gitudinay' 'as iuustrated at Il, four of said splits equally distant apart being shown. 40

The necks 9 are inserted in the ends ofl the f stems 1 and the necks are provided with an annularly arranged series of longitudinally disposed ribs I2 which mate with slots I3 cut in the 'bores of the stems tor prevent relative rotary 45 movement between the stems and the heads.

Il represents tapered bolts fitting the openings of the necks 9 so that when the necks havey been inserted into the stems with the heads bearing against or adjacent to the ends of the stems, nuts I5 may be screwed up tight on the threaded ends of the bolts I4 against the heads, thus wedging the split necks into fixed engagement with the stems and the corresponding head will y rotate in unison.

.Suitable locks are applied to the nuts I3 to prevent them from loosening.

Each of the heads 8 is provided with a pair of radially extending and preferably diametrically opposed lingers IG and I1. The hub is circumferentially enlarged as at 8a to provide' heads 8 and the fingers I8 and consequently the degree of pitch variation.

'I'hus by adjusting the bolt I3 the minimum pitch of the corresponding propeller blade may be regulated and likewise the bolt I3 determines the maximum pitch of the blade.

20 represents a helical spring mounted in a v socket 2l formed in the wall of the hub and the inner end -of said spring bears against the finger I1. This. spring is arranged so that it tends to rotate the head 8 to reduce the pitchv of the corresponding propeller blade to the minimum determined by the adjustment `of the bolt I8.

22 represents a cylinder also formed in the` wall of the hub at each enlargement 8a and opposed to the corresponding spring socket 2|. The outer ends of each of the cylinders are closed and 23 represents a piston'working in the cylinder and provided with a suitable packing such as the expanding cup 24.

25 represents a piston rod having one end provided with a ball 26 which is received in a cup socket in the inner end of the piston while the other end of the rod'` is provided with a second ball 21 which is seated in a similar socket in the finger I1.

23 is an outwardly flaring hole extending from the socket through the finger and 23 is an extension of the rod working in the said hole, thus preventing the rod from dropping out of place While permitting its flexible action between the piston and the finger.

As may be seen in Figure 1, the arrangement of the spring and the piston is reversed in the case'of the two propeller stems. The closed ends of the two cylinders 22 are connected by passages' 3|), preferably formed in the walls of the hub parts with longitudinal grooves 3| cut in the perimetral surface of the shaft I, and said grooves are connected by radially disposed passages 32 in the shaft with the longitudinal passage 33 at the axis of the shaft. The outer end of said passage 33 is closed.

The passage 33 extends rearwardly in said shaft for a short distance and then ends or is blocked; 34 "fs a radial passage formed in the shaft and connected at its inner end with the passage 33. A short distance in the rear of the passage 34 said shaft is provided with a second radial passage 35 which connects at its inner end with a second axial passage 3G whose rear end is connected with the oil pressure system of the motor.

31 represents a valve casing which is fixed. For

instance, it may be mounted on a portion of the motor' frame. The casing is provided with a horizontal bore 3B through which the shaftV I extends, packing rings or gaskets 39 being employed to prevent the escape of oil from the valve casing along the shaft in either direction.

, The casing 31 is provided with a horizontal passage 40 having its ends. connected portions with annular grooves 4I out in the wall of the bore 31 and registering respectively with the radial passages 34 and 33 in the shaft.

.42 represents a valve plug seated in a valve seat 43 which intersects the passage 40, so that the oil pressure may be admitted to the cylinders 22. be cut oif therefrom, .or by aA partial closing of the valve the oil pressure eftective at said cylinders may be regulated.

The valve plug 42 is preferably operated from the cockpit or control station of the aeroplane or other aircraft. Thus I have 'indicated the valve plug provided with a crank 44 and the lever 43 extending rearwardly past the motor 2 so that the operator may open or close or regulate the valve while the aeroplane is in flight.

It ls obvious that as the speed of rotation increases with the increasing speed of the motor, the oil pressure e'ective in the cylinders 22 will increase, thus increasing the pitch of the propeller blades, the springs 20 being compressed. Likewise as the speed of rotation of the propeller decreaseswith the decrease ofthe speed of the motor, the oil pressure eiective in said cylinders will decrease and the pitch of the propeller blades will correspondingly decrease owing to the expansion of the springs 2|).

By means of the abutment', bolts I3 and I 9 the minimum pitch and the maximum pitch may be adjusted to obtain the desired eiiects.

Y By means of the manually operated valve in the pressure supply passage, the oil pressure may bev cutoff from the cylinders 22 for taking oil' and/or for landing and by the adjustment of the valve any desired pressure may be rendered eil'ective in said cylinders.

It is obvious that my invention may be used in connection with any suitable manual control of the pitch. It is well known that aeroplane propellers of the adjustable type tend to lose pitch by reason of centrifugal force developed within the propeller blades, producing a torque on the axis of the blade while in operation, which tends to cause them to move toward a low pitch position. Therefore it may be said that Amy springs 20 assist or augment this force.

The cylinder 22 may be termed a iluid container, and the piston operates therein in response to increase and decrease of uid in this container.

In addition to the adjustable stops I8 and` I9 for limiting the range of movement of the pitch variation, it will be noted that the end of the cylinder 22, and the end of the socket for the spring 20 are positioned so as to constitute permanent positive stops effective with the finger I1.

I claim:

1. In variable speed -propeller mechanism for aeroplane and the like uses, the combination with a motor provided with an oil supply under pressure which varies with the speed of the motor, a shaft driven by said motor and provided with a longitudinally disposed oil passage ln communication with the oil supply, a hub xed on and f disposed transversely to said shaft, the ends of said hub being provided with bores, propeller 'adjacent each of said bores and communicating with the latter, the outer ends of each of said cylinders being connected by a passage in the hub communicating with the shaft passage, pistons Working in said cylinders and provided with piston rods, a`radial1y disposed iinger carried by each of said stems and engaged by the piston rod o-f the corresponding piston, the arrangement being such that as the Yoil pressure increases with the increasing speed of the motor the stems are rotated toi`ncrease the pitch of the blades, and means for automatically decreasing the blade pitch as the oil pressure decreases.

2. In variable speed propeller mechanism. for aeroplane and the like uses, the combination with a motor provided with an oil supply under pressure which varies with the "speed of the motor, a shaft driven by said motor and provided with a longitudinally disposed oil passage in communication with the oil supply, a hub xed on and disposed transversely to said shaft, the ends oi said hub being provided with bores, propeller.

blades having stems journalled in said bores and arranged for rotation relative to the hub to vary the pitch of said blades, a cylinder in said hub adjacent each of said bores and communicating with the latter, the outer ends of each of .said cylinders being connected by a passage in the hub communicating with the shaft passage, pistons Working in said cylinders and provided with piston rods, a radially disposed finger carried by each of said stems and engaged by the piston' rod of the corresponding piston, the arrangement being such that as the oil pressurel increases with f the increasing speed of the motor the stems are rotated to increase the pitch of the blades, and

a spring Working against each of said lingers andopposed to the corresponding piston whereby to decrease the blade pitch as the oil pressure decreases. Y f

3. In variable speed propeller mechanism for aeroplane and the like uses, the combination with a motor provided with an oil supply under pressure which varies with the speed of the motor, a shaft driven by said motor and provided with a longitudinally disposed oilgpassage in communication With the oil supp-ly, a hub fixed on and disposed transversely to said shaft, the ends of said hub being provided with boxes, propeller blades having stems journalled in said boresrand arranged for rotation relative to the hub to vary the pitch of said blades, a cylinder in said hub adjacent each of said bores and communicating With the latter, the outer ends of, each of said cylinders being connected by a passage in the hub communicating with the shaft passage, pistons Working in said cylinders and provided with piston rods, a. radially disposed finger carried by each of said stems andengaged by the piston rod of the corresponding piston, the arrangement being such that as the oil pressure increases with the increasing speed of the motor the stems are rotated to increase the pitch of the blades, means for automatically decreasing the blade pitch as the oil pressure decreases, and means for regulating the oil pressure effective against the pistons.

4. In variable speed propeller mechanism for aeroplane and like uses, the combination with a motor provided with an oil supply under pressure which varies with the speed of the motor, a shaft driven by said motor and provided with a longitudinally disposed oil passage/ in communication with the oil supply, a hub iixed on and disposed transversely to said shaft, the ends of said hub being `provided with bores, propeller blades having stems journalledin said bores and arranged for rotation relative to the hub to vary the pitch of said blades, a cylinder in said hub adjacent each of said bores and communicating with the latter, the outer ends of each of said cylinders being connected by a passage in the hub communicating with the shaft passage, pistons working in said cylinders and provided with piston rods, a radially disposed iinger carriedv by each of said stems and engaged by the piston rod of the corresponding piston, the-arrangement being such that as the oil pressure increases with the increasing speed of the motor the stems are rotated' to increase the pitch of the blades, means for automatically decreasing the blade pitch as the oil pressure decreases, and means for limiting the increase of the blade pitch in response to increasing oil pressure.

5'. In variable speed-propeller mechanismfor aeroplane and like uses, the combination with a motor provided with an oil supply under pressure which varies with the speed of the motor, a shaft driven by said motor and provided with a longitudinally disposed oil passage in communication with the oil supply, a hub fixed on and disposed transversely to said shaft, the ends of said hub being provided with bores, propeller blades having stems journalled in said bores and arranged for rotation relative to the hub to vary the pitch of said blades, a cylinder insaid hub Aadjacent each of said bores and communicating with the latter, the outer ends of each of said -cylinders being connected by a passage in the hub communicating with the shaft passage, pistons Working in said cylinders and provided with piston rods, a radially disposed fingerV carried by each, oi?` said stems and engaged by the piston i rod of thewcorresponding piston, the arrangement being with. the in are rotated to increase the pitch of the blades, means for' automaticallyA decreasing the blade pitch as the oil pressure decreases, means for limiting the increase of the blade pitch in reh that as the oil pressure increases 'ng pitch of the motor the stems sponse to increasing oil pressure, and means for varying the minimum pitch of the blade..

' JormiaAPP zIPAY. 

